1. Field of the Invention
The present invention relates to a light emitting diode and a method of fabricating the same. More particularly, the present disclosure relates to a light emitting diode that includes a plurality of light emitting cells, wires connecting the light emitting cells to each other, and dielectric layers for protecting the light emitting cells and the wires, and to a method of fabricating the same.
2. Discussion of the Background
Since gallium nitride (GaN)-based blue light emitting diodes (LEDs) were developed, attempts have been made to improve luminescent efficiency of these LEDs, and a variety of structural improvements for various applications have been proposed. GaN-based blue or ultraviolet (UV) light emitting diodes are widely used for applications, such as natural color LED devices, LED traffic signal boards, white LEDs, etc., and may replace white fluorescent lamps in the field of general lighting.
A light emitting diode may emit light by application of a forward current and may require a direct current power supply. In consideration of characteristics of the light emitting diode operating by the forward current, light emitting diodes have been developed which include a plurality of light emitting cells connected in reverse parallel or operated using a bridge rectifier, and which operate using an alternating current power source. Further, light emitting diodes have been developed which include a plurality of light emitting cells formed on a single substrate and are connected in series and in parallel to emit light with high-output and high-efficiency using a high-voltage direct current power source. In these light emitting diodes, the plurality of light emitting cells may be formed on the single substrate and connected via wires to emit light with high-output and high-efficiency using the alternating or direct current power source.
One example of the light emitting diodes including the plurality of light emitting cells connected to the high-voltage alternating or direct current power source is disclosed in Sakai, et. al., WO 2004/023568 A1, entitled “light-emitting device having light-emitting elements,” which is hereby incorporated by reference for all purposes as if fully set forth herein.
The light emitting cells may be connected to each other by air bridge wires, thereby providing a light emitting diode which can be operated by the alternating or direct current power source.
However, an interconnection between the light emitting cells via the air-bridge wires may cause the wires to deteriorate, that is, problems such as disconnection of the wires or increase in wiring resistance due to moisture or impact from the outside. To prevent such problems, a wire connection technology based on a step-cover process may be adopted. The step-cover process includes forming wires on a dielectric layer covering the light emitting cells. Since the wires are located on the dielectric layer, they may be more stable than the air-bridge wires.
However, the wires formed by the step-cover process may be exposed to the outside and may also be disconnected by moisture or external impact. The light emitting diode having the plurality of light emitting cells includes a number of wires and cannot be operated if any one of the wires is disconnected. Furthermore, since a number of wires are used in the light emitting diode, moisture may intrude into the light emitting cells along the wires, thereby deteriorating luminescent efficiency of the light emitting cells.
When the light emitting diode is used for practical applications such as general lighting and the like, there is a need to realize a variety of colors such as white light through conversion of UV or blue light into light having longer wavelengths via fluorescent materials. Conventionally, such fluorescent materials may be contained in an epoxy which covers a light emitting diode that emits short wavelength light in a package. For such a white light emitting diode, a color-conversion material layer containing the fluorescent materials may be formed during a packaging process, which is independent of a process of fabricating the light emitting diode chip, so that the packaging process may become complicated, thereby causing a high failure rate in the packaging process. Failures that occur during the packaging process may be more expensive than those that occur during the process of fabricating the light emitting diode chip.